JPS5838025B2 - Irojiyouhokenshiyutsu warmer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color information detection circuit that detects a portion of a color image signal having hue, saturation, and brightness within a predetermined range.

When producing television broadcast programs, a so-called chromakey technique is often used to partially insert one screen into another screen to form a composite screen.

That is, from the color image signal, as shown in FIG.
Further, it detects and extracts an image signal of a portion having color information within a range surrounded by diagonally shaded portions X1 and X2 in the figure, which has brightness within a predetermined range M1 to M2, and uses the detected output signal as a gate signal. A method of screen merging is often used in which a signal portion extracted from another color image signal is inserted into the next color image signal.

As mentioned above, in order to detect only color information signals in a predetermined range, a line chroma key signal using the NTSC color television system has been used. , from among the color signals appearing on the screen of the vectorscope, the color difference signal R-
For Y (Y indicates a certain portion of the luminance signal), the signals within the range between ■ and ■ are used, and for the color difference signal B-Y, signals within the range between H and H are sliced and extracted. .

However, if the signal level of the image signal changes due to an increase or decrease in the amount of light incident on the color camera or a change in the gain of the amplifier, the above-mentioned slice level will change, although the shape of the chromakey signal is easy. The range of color information of the color signal to be taken will vary.

In order to prevent such variation in the sampling range, it is necessary to normalize the color signal based on the luminance signal level.

As mentioned above, in order to normalize the signal level of the color signal in a color image signal by the luminance signal level, conventionally,
It was considered to use a division circuit, but using a division circuit would make the circuit structure for the above-mentioned normalization extremely complicated, and the circuit operation would also become unstable and uncertain. If the signal level of the color signal is normalized by division by the luminance signal level, it becomes impossible to specify the brightness range and extract the color signal.

An object of the present invention is to solve the above-mentioned problem and to detect the hue and chroma within a predetermined range without using a division circuit in order to normalize and detect the signal level of the color signal in the color image signal by the luminance signal level. After detecting and extracting a color signal with a specific brightness, by further extracting only a color signal with a brightness within a predetermined range, only a color signal with a predetermined hue, saturation, and brightness can be extracted stably, reliably, and easily. An object of the present invention is to provide a color information detection circuit configured to obtain color information.

Another object of the present invention is to provide a color information detection circuit that is capable of reliably performing chroma keying by extracting an image signal having a predetermined hue and saturation regardless of the brightness of the image using a simple circuit configuration. Our goal is to provide the following.

That is, the color information detection circuit of the present invention has at least one color signal formed by separating a color image signal, and signal levels corresponding to the upper and lower limits of a predetermined range regarding the hue and saturation of the color signal, respectively. At least two luminance signals and comparing signal levels with each other, respectively.
a gate signal type control circuit having a plurality of comparators and at least one AND gate circuit which inputs the comparison outputs of these comparators; and a gate controlling the color image signal by controlling the gate signal type or circuit. By providing a circuit and an integrating circuit that integrates the gate output signal of the gate circuit over a predetermined period and averages the signal level, a color signal having a hue and saturation within a predetermined range can be obtained as the integrated output of the integrating circuit. This is characterized in that the average value of the signal level of the included color image signal is normalized by the luminance signal so that it can be stably detected without being affected by noise.

The present invention will be explained in detail below with reference to the drawings.

First, as shown in FIG. 3, color difference signals R-Σ and B-Y are normalized by a luminance signal Y, similar to the color signals displayed on the screen of a conventional vectorscope.
Y ″Ichigo,.

-JbffleJz,l Q Table 51 is 3''8°, and for the T axis, k1 to k2) For the y axis, a color signal within the range of l1 to l2 can be expressed by the following equation.

In the configuration example of the gate pulse generation circuit for color information detection according to the present invention shown in FIG. I am trying to form it by combining these.

That is, in the example of the structure shown in FIG. 4, for example, various imaging output signals of a color television camera are added to a color encoder to generate color difference signals R-Y and B-.
Y and luminance signal Y were first amplified by amplifiers 1, 2, and 3, respectively, and their respective gains were appropriately adjusted by potentiometers 4, 5, and 6, and then clamp circuits 7, 8, and 9 were attached, respectively. They are led to amplifiers 10, 11, and 12, respectively.

In this case, at the outputs of amplifiers 10, 11, 12,
The potentiometers 4. Adjust it.

Next, the luminance signal Y of the output of the amplifier 12 adjusted as described above is transmitted to the potentiometers 15, 16, 17.
, 18, the respective gains are adjusted to the predetermined values k1, k2, A, , l2 shown in FIG. , 22.23, 24.

On the other hand, the color difference signal R-Y output from the amplifier 10 is added to the comparators 21 and 22, and the color difference signal B-Y output from the amplifier 11 is applied to the comparators 23 and 24, and the gain is adjusted in each comparator as described above. If the signal level is compared with the luminance signal Y obtained by using the appropriate polarity, each comparator 21, 22
, 23, and 24 are each given the above equation (3) t
(4) t A color difference signal BY or RY that satisfies the conditions of (6) and (5) is obtained.

Therefore, these comparator outputs are respectively A
When added to the ND gate circuits 27 and 28, the respective gate outputs have k1 to k2 that simultaneously satisfy the conditions of equations (3) and (4) and (5) and (6).
Gate signals are obtained by normalizing the color difference signal R-Y in the range of and the color difference signal B-Y in the range l1 to l2 by the luminance signal Y, and normalized colors having hue and saturation within a predetermined range are obtained. A gate signal corresponding to the signal can be obtained.

Of the color signals having a predetermined hue and saturation extracted by gate pulses shaped as described above, a color signal having a brightness within a predetermined range is controlled depending on changes in the signal level of the luminance signal. In order to stably and reliably take out the information without any interference, the following signal processing is performed.

That is, when a certain instantaneous value of the luminance signal Y is y and the peak value is yp, the color signal corresponding to the luminance signal level y that satisfies the condition y m < 1 < m2 (7) "Y," is as follows.
Since it has a brightness within a predetermined range of m1 to m2, and this brightness range is normalized by the peak value Y of the brightness signal, it is unrelated to changes in the brightness signal level.

Therefore, in the gate pulse generation circuit for color information detection according to the present invention, in order to detect a color signal that satisfies the condition of the above-mentioned equation (7), there is no need to use a division circuit as shown in equation (7). As in the case of detecting a color signal having hue and saturation within a predetermined range described above, a combination of a comparator and an AND gate circuit is used to form a gate pulse for detecting color information.

That is, in the circuit configuration shown in FIG. 4, the human-powered luminance signal from the luminance signal amplifier 12 is guided to the peak detector 13, and its detection output is held and guided to the amplifier 14, giving it at least the same gain as the amplifier 12. The above-mentioned peak level luminance signal yp is obtained as the output thereof.

The peak value Yp of this luminance signal is set by the potentiometer 19.
, 20, respectively, the above-mentioned brightness ratio rn1 2m2
after adjusting the gain to the comparator 25.
, 26, and perform a level comparison with the instantaneous luminance signal y from the amplifier 12 with appropriate polarity.If each comparison output is applied to the AND gate circuit 29, the above-mentioned equation (7) is shown as the gate output. A gate signal is obtained that corresponds to the normalized brightness of the range.

Therefore, the hues in the ranges k1 to k2 and l1 to l2 shown in the third diagram obtained from the AND gate circuits 27 and 28,
a gate signal corresponding to a normalized color signal having chroma, and A
If the gate signal corresponding to the normalized lightness in the range of m1 to m2 obtained from the ND gate circuit 29 is added to the AND gate circuit 30, the gate output will be expressed by the above equation (1
), (2), and (7), and corresponds to a normalized color signal having hue, saturation, and brightness within a predetermined range, and corresponds to a signal of a portion of the color image signal that has the normalized color signal. A gate signal for extracting only the signal can be taken out from the output terminal 31.

In the configuration example shown in the fourth figure described above, the color signal to be detected is expressed by two-axis coordinates using color difference signals R-Y and B-Y, but R, B, G from a color television camera etc. FIG. 5 shows an example of a circuit configuration in which a gate signal for extracting a color signal having a predetermined range of hue, saturation, and brightness directly from a three-primary color image signal by normalizing it with a luminance signal is obtained.

The circuit configuration shown in Figure 5 has hue and saturation in the ranges k1 to k2, l1 to l2, and n1 to n2 from the R, G, and B primary color signals, respectively, in exactly the same way as in the configuration shown in Figure 4. While forming gate signals corresponding to the normalized color signals, these three primary color signals are connected to resistors r1 2
The luminance signal component W mixed at a predetermined ratio by r2 2 r3 and r4 is formed as the output of the mixing amplifier 32, and this luminance signal component W has a normalized brightness range exactly the same as in the previous example. The gate signals corresponding to m1 to m2 are output, and the gate signals corresponding to the normalized color signals having hue, saturation, and lightness within these predetermined ranges are taken out from the output terminal 31 as gate outputs of the AND gate circuit 30.

Note that for a color signal expressed by any desired coordinate system such as the I and Q axes, a required gate signal for normalized color signal extraction can be formed in exactly the same manner as described above.

In addition, in each of the above configuration examples, a potentiometer was used to set the luminance signal level to normalize color information in a predetermined range, but these signals are encoded and a multi-type digital-to-analog converter is used. These signal levels can also be set using the .

As described above, in order to form a gate signal corresponding to a color signal having a predetermined hue and saturation according to the present invention and to detect an image signal level in a specific portion of a color image using such a gate signal, It is necessary to remove the influence of noise to accurately, reliably and easily detect the average image signal level of the relevant portion.

In order to accurately detect the image signal level, there has conventionally been an image signal level measurement circuit that combines a sample holder and an analog/digital converter to encode and process the image signal. - Some digital converters use a sequential comparison type, and are combined with an electronic computer to integrate and process a large amount of data to improve measurement accuracy. There are also digital voltmeters that use an integral type.

However, the former requires an expensive electronic computer capable of high-speed processing, and the latter requires a large amount of time for integration and requires the use of a sample holder in order to improve measurement accuracy.

In order to eliminate these conventional drawbacks, the image signal at the measurement point in the image can be gated, added to an integrating circuit, and integrated over an appropriate period of time depending on the signal level. Furthermore, even if a relatively slow analog-to-digital converter and a slow, inexpensive electronic computer are used, it is possible to reliably and easily obtain the average value of the image signal level from which the influence of noise has been removed.

For example, the average value of the image signal level in an image having a shape as shown in FIG. 6 is determined using a circuit configuration as shown in FIG. 44, and the input image signal S is gated by a gate pulse from a gate pulse generation circuit 42 which is also driven by adding the input image signal S.

Accordingly, as illustrated in FIGS. 4 and 5, the gate pulse generating circuit 42 is provided with a desired hue,
For example, with respect to the image shown in FIG. 6, an image portion having color information i1 to io is obtained by using a gate signal forming circuit that extracts an image signal of only an image portion having saturation or brightness and forms a gate signal. The image signal of is taken out as the gate output of the gate circuit 44, and as shown in FIG. .

When the image signal (2) containing noise in such a waveform is added to and integrated by an integrating circuit consisting of, for example, a differential amplifier 46 with a gain of A, a resistor R, and a capacitor C, the output Σeo of the integrating circuit is expressed by the following equation (8). It will be shown in .

Here, im is from tm to tm in one horizontal scanning period IH.
After repeatedly detecting and integrating the gate output current over N fields, the switch S1 connected in parallel to the integrating capacitor C is reset by the reset circuit 48. Drive to close and reset the integral.

Generally, when a signal containing random noise is integrated through M circuits, the signal-to-noise ratio S/N is improved by 10 logMdB, and the above-mentioned integrating circuit also achieves a similar improvement in the signal-to-noise ratio.

However, if only the above-mentioned integration is performed, the integrated value will vary depending on the period during which the image signal is gated.
For example, this does not mean that the average value of the image signal level has been determined for the entire figure as shown in FIG.

In order to eliminate the average value error due to the difference in gate periods, as shown in FIG. A reference DC voltage is applied to the gate circuit 44 in exactly the same manner as described above, and has a reference level appropriately set as shown in FIG. 8b, and has a waveform as shown in FIG. 8a. A reference signal (■) that is intermittent for exactly the same period as the image signal (■) is used.

In addition to this reference signal (2), an integrating circuit consisting of a differential amplifier 47 with a gain of A, a resistor R, and a capacitor C, and configured in exactly the same way as the integrating circuit for the above-mentioned image signal (2),
Integrating with exactly the same integration time constant as the image signal ■,
The output Σe8 of the integrating circuit is then outputted to the reset circuit 48 in the configuration of FIG. 7a, as shown in FIG. When the integral output Σeo of the signal reaches a predetermined value k, a reset pulse is generated and each integrating circuit is reset by switches S and S2. , the reset time t for the integral output Σeo1 when the gate period is long.

-t1 is shortened, and is the reset time t for the integral output Σeo2 when the input image signal level is low or the gate period is short.

-t2 becomes long, so if the aforementioned integration number M is chosen to be large, an appropriate integration period will be automatically set according to the level of the input image signal, etc., and the signal-to-nozzle ratio can be substantially improved. , it is possible to eliminate the influence of noise and fluctuations due to differences in gate periods, thereby preventing deterioration in measurement accuracy of the average image signal level.

According to the structure of the image signal level average value detection circuit shown in FIG. When determining the image signal level of , that is, color information such as brightness, hue, saturation, etc.,
A signal level detection circuit having a structure as shown in the figure can be used.

In the circuit configuration shown in FIG. 9, the three primary color image signals R, B, G are clamped and gate circuits 44, 53 . At the same time, the gate pulses are led to the gate pulse generation circuit 42 to generate gate pulses corresponding to predetermined color information, and the respective image signals gated by the gate pulses are added to the respective integration circuits to generate the three primary colors. The integral value of the image signal and the reference signal similar to the above example is extracted.

These integral outputs make it easy to stably and reliably obtain the required color information.

As is clear from the above description, according to the present invention, the following remarkable effects can be obtained.

(1) Since a color signal having an arbitrary range of hue, saturation, and brightness can be stably and easily extracted from a color image signal regardless of the level of the luminance signal, a chromakey signal can be reliably and easily obtained. .

(2) Since there is no need to use a division circuit to normalize the color information signal, the configuration of the color information detection circuit is simplified.

(3) Since it is possible to extract color signals with a limited range of lightness as well as hue and saturation, gain control and
Various signal level controls such as vedestal level control become easy.

(4) By using the image signal level detection circuit as a gate pulse generation circuit, a wide range of application fields such as automatic adjustment of color temperature and automatic adjustment of skin tone for color images can be developed.

Furthermore, the following effects can be obtained by the image signal level detection circuit used for color information detection according to the present invention.

(5) Since the same gate pulse is used in the gate circuits for the reference power source and the image signal to be measured, measurement can be performed with good accuracy even if the area of the part to be measured in the image changes.

(6) Since the integration period is changed according to the signal level of the image signal to be measured, deterioration of measurement accuracy due to noise can be prevented.

(7) Since the average value of the signal level of the gated portion of the image signal under test is detected, accurate signal level detection can be performed without being affected by shading or streaking contained in the image signal. .

(8) Since the average value of the image signal level over a wide area can be determined without calculating from a large number of measured values as in the conventional method, the average value can be easily detected.

[Brief explanation of the drawing]

Fig. 1 is a line diagram showing the form of color information to be detected in the present invention, Fig. 2 is a line diagram showing the form of the conventional chromakey signal, and Fig. 3 is a line diagram showing the form of the chromakey signal according to the present invention. 4 is a block diagram showing an example of the structure of a gate pulse generating circuit for color information detection according to the present invention, and FIG. 5 is a block diagram showing another example of the structure of the gate pulse generating circuit according to the present invention. FIG. 6 is a diagram showing the aspect of an image targeted for detection of the average value of the image signal level according to the present invention, and FIG. 7a
and b are block diagrams and operational waveform diagrams respectively showing an example of the structure and mode of operation of the image signal level average value detection circuit according to the present invention, and FIGS. FIG. 9 is a block diagram showing another example of the structure of the image signal level average value detection circuit according to the present invention. 1, 2, 3...Amplifier, 4, 5, 6...
- Potentiometer, 7, 8, 9...clamp circuit, 10, 11, 12, 14... amplifier,
G3...Peak detection circuit, 15, 16, 17,
18, 19, 20... Potentiometer, 2
L22, 23, 24, 25, 26... Comparator, 27, 2B, 2930... AND gate circuit, 31... Output terminal, 32...
Amplifier, 33... Potentiometer 34...
... Clamp circuit, 35 ... Amplifier, 36
, 37... Potentiometer, 3B, 39.
... Comparator, 40 ... AND gate circuit, 41 ... Clamp circuit, 42 ...
...Gate pulse generation circuit, 43...Reference power supply, 44, 45...Gate circuit, 46,4
7... Differential amplifier, 48... Reset circuit, 49, 50... Output terminal, 51, 52...
... Clamp circuit, 53, 54 ... Gate circuit, 55, 56 ... Differential amplifier, 57,
58...Output terminal, rl t r2 t r
3j r4 t R6+++++ resistance, S1, S2, S
3, s4...Switch, C...Capacitor.

Claims (1)

[Claims] 1. The signal levels of at least one color signal formed by separating one color image signal and a luminance signal each having a signal level corresponding to the upper and lower limits of a predetermined range regarding the hue and saturation of the color signal, respectively. A gate signal type or circuit having at least two comparators for mutual comparison and at least one AND gate circuit which inputs the comparison outputs of these comparators, and controlled by its gate signal forming circuit, By providing a gate circuit that gates a color image signal and an integration path that integrates the gate output signal of the gate circuit over a predetermined period and averages the signal level, hues in a predetermined range can be obtained as the integral output of the integration circuit. and a color information detection circuit characterized in that the average value of the signal level of a color image signal including a color signal having chroma is normalized by a luminance signal so as to be stably detected without being affected by noise.